This application discloses an invention which is related, generally and in various embodiments to vacuum loading systems.
In the plastic industry it is common practice to transport material such as plastic pellets from a source of material such as a storage bin to the hopper of a hopper loader by applying a vacuum to the hopper with a vacuum generator. When an appropriate amount of material has been received in the hopper of the hopper loader, the material conveying is discontinued by discontinuing the applied vacuum and thereby permitting the material in the hopper to be gravitationally discharged through a material outlet of the hopper loader in communication with the hopper. Presently, the length of time to convey is determined by either setting a load timer on a control or using a material sensor to determine when the hopper is full. The problem with setting the timer is that 1) it's a manual function that is empirically determined; and 2) changes to the process require adjustment. The problem with using a sensor is that 1) the sensor may be deceived by material clinging to it due to static electricity; 2) the sensor must be in contact with the material or be in “line of sight”; and 3) may be eroded due to contact with the material. The invention seeks to solve the problems associated with determining the proper load time for a hopper loader that are encountered by empirical and material sensing methods.